Preparation of two different lube oil fractions by single solvent extraction



H. o. BUTTON ETAL 3,488,283 PREPARATION OF TWO DIFFERENT LUBE OIL FRACTIONS Janrfi, 1970 BY SINGLE SOLVENT EXTRACTION Filed March 28, 1968 3 E :0 c E z q ESQ Sou 0m m 2 $63 5 S H m m W mv W u 6 VA W D 220m m: ww O A. mvw %M h. m5 tEtQ M mm 9v mm N H 0 6; mm 1% 9n 6 o QM, mmmgm W 55 QM m y $858 08 mm m N 5 50 UPON m V moo v. mOQ S8 mt mom a 28w l $02 300i m 91 m m N\ sm & Q NE/ m 892m 9w x Q w o u; mQTvw u000m A j mnw moootmnw mi 0 %m+ vow, \omv T Q 3mm mom ww NW mom a mw N62 528: 02 6 05 ocmxozmo 8:02am. 3:5 Q30 5 22: 5

United States Patent ABSTRACT OF THE DISCLOSURE A multi-step solvent extraction process is described for the preparation of lube oil products wherein the selectivity of the solvent is maintained in at least one of the extraction steps suitable to yield a rafiinate lube oil product which has the equivalent of a light neutral V'.I; level of at least about 120 V.I. after dewaxing and effecting the extraction in a process environment which will substantially reduce the solvent dosage required'to produce the high V.I. oil product in combination with a lowerV.I. oil product and often raise the yield of the desired oil products.

Background of the invention Solvent extraction is a well established process used in the refining of petroleum, thefirst application having been made in about 1911. Originally, upgrading of kerosine was a major use but the improvement obtained in solvent extracting lubricating oils .and others soon became an important application. Solvent extraction is used extensively in the petroleum refining industry to refine lubricating oils, kerosine andv specialty oils for medicinal and agricultural purposes. Solventextraction has'also been used for the upgrading of charge stocks for catalytic cracking operations as well as the separation of light aromatics from gasoline. Solventextraction is a process that separates hydrocarbon mixtures into tWo phases; a rafiinate phase which contains substances of relatively high hydrogen to carbon ratiooften called parafiinic typema terials and an extract phase which contains substances of relatively low hydrogen to carbon ratio. often called aromatic type materials. Therefore, it maybe said that solvent extraction ispossiblebecausedifierentliquid compounds have different solution afiinities for each other and some combinations are completely'miscible while other combinations are almost immiscible. Theability to distinguish between high carbon to hydrogenaromatic type and low carbon to hydrogen or paraffinic type materials is termed selectivity. The more finely this distinguishing can be done the higher the selectivity of the solvent.

For example, it is known that lube oils are exceedingly complex hydrocarbon mixtures made up principally of paraffins, naphthenes, aromatics and asphalts and the chemical constitution of oils stable to oxidation can only be guessed. That is, it is known that the polynaphthenic type materials oxidize more readily to-degradation products such as acids and/or insoluble asphaltenes than do those of parafiinic type. The latter usually tolerate oxidation at moderate temperatures for extended periods before visible signs of change appear, but it is not clear or certain that soluble oxidation products are not accumulating during this period. In agreement with this is the fact that the oxidation of mixed naphthenic oils is retarded by solvent extraction which removes the polynaphthenes and polyaromatics.

It is known from work of others that oil is made up of compounds consisting of naphthenic and aromatic rings carrying side chains of varying number, length and structure. Long side chains are characteristic of molecules of high paraffinicity and high viscosity index, while poly- 3,488,283 Patented Jan. 6, 1970 naphthenic and polyaromatic structures with fewer and shorter chains will show low viscosity index, high viscosity-gravity constant and relatively poor stability against oxidation. The division between compounds of long and short side chains, therefore, is necessarily not sharp and undoubtedly some constituents of good quality are lost in any extraction process.

Terms which are used extensively in solvent extraction operations include solvent for the extracting agent, solute for the readily soluble material in the feed, extract for the material removed from the feed, raflinate for the non-dissolved product, and reflux for extract material returned to the extractor. Lean solvent refers to the solvent as charged to the extractor; rich solvent refers to the solvent extractsolution withdrawn from the extractor.

Solvents which have been used in commercial operations include furfural, phenol, cresylic acid, nitrobenzene, dichloroethyl ether, sulfur dioxide and others. If desired, these solvents may be used in the presence of diluents such as benzene, carbon disulfide, ethers and carbon tetrachloride. Generally the diluents increase the solubility of all of the hydrocarbons. The use of diluents however can reduce solvent selectivity.

Furfural is typical of a suitable solvent extraction agent. Its miscibility characteristics and physical properties permit use with both highly aromatic and highly paraflinic oils of wide boiling range. Diesel fuels and light and heavy lubricating stocks are refined with furfural. For lubricating oils it has been used in the prior art at elevated temperatures in the range of 120 F. to 290 F. and with from 1 to 4 volumes of furfural to 1 volume of oil. Furfural exhibits good selectivity at elevated temperatures (US-250 F.); this characteristic results in the benefits of reduced viscosity and high temperature gradient and permits operation on waxy stocks. In a typical furfural solvent extraction plant for lubricating oils, the raw feed or distillate fraction, at a temperature of about 110 to about 250 F. and depending upon the nature of the oil, is introduced below or about the center of the extraction tower. Furfural is fed into the top or upper portion of the tower at a temperature selected from within the range of about 150 F. to about 290 F. Recycle extract may be introduced into the lower section of the tower as reflux. Likewise, internal reflux is effected in, the tower by the temperature gradient which is brought about by introducing the solvent at an elevated tempenature and by intermediate cooling systems. Furfural solvent is recovered from the rafiinate and extract phase streams or layers in suit-able distillation and stripping equipment. The stripped and recovered solvent is then returned or recycled for use in the process as above described.

Finished lubricating base oils are generally divided into the following three broad grade classifications:

Viscosity Range,

Saybolt Seconds Universal Boiling Range, F.

Light neutrals -250 at 100 F 650-900" F. Heavy neutrals... 350-700 at 100 F 850l,000 F. Bright stocks -200 at 210 F- 950 F.

more difiicult to refine to a given viscosity index level conditions described in this invention, high viscosity index products from a given crude will vary with viscosity grade as follows:-'

High viscosity index product, plus These numerical V.I. levels thus represent equivalent extraction severities' for the several viscosity grades of products. The V.I. rating of lubricating oil products can then [be generally described in terms of any one of these viscosity grades in accordance with this relationship.

Lube crude oils are classified by the Bureau of-Mines into three categories according to .the predominant-composition of their 736-788 F. fraction'as paraffinic, intermediate and naphthenic. Parafiinic crude such as Pennsylvania or High Pour Libyan crudes contain considerable amounts of wax, while some'naphthenic crudes such as coastal crudes contain no wax. Intermediate crudes such as Mid-Continent, Kuwait or East Texas contain varying amounts of both wax. Thus it can be seen that crude source is especially important in the manufacture of premium lubricants as various lubrication duties require oils of different chemical composition and properties.

Results of a relatively broad literature review indicate than is the adjacent lower boiling fraction. Therefore underthe that relatively high V.I. lube oil components and above about 120 V.I. are present in many crude lube oil fractions. However, recovery of these high V.I. components in a stable oil fraction has been the subject of considerable investigation. It has been found upon review of the prior art and literature methods for recovering high V.I. lube oil constituents that the processes employed are generally regarded as exotic extraction and distillation schemes which are of little or no commercial interest primarily because of cost involved.

It has been demonstrated that a 125 V.I. oil can be 5 Basically all extraction processes are similar. Each con- H sists of facilities to contact the oil with a selective solvent that separates by extraction one or more types of the oil constituents from other types of oil constituents plus facilities to separate solvent from the extract and raffinate P streams thus obtained. The solvent must be. recovered in substantially every circuit of the system. As large amounts of solvent are circulated, the heat requirements are high and unless employed in extremely efficient manner, they constitute onerof the major operating expenses.,The. ex: *1

traction equipment proper is relatively simple but the solvent recovery facilities are necessarily complex and therefore expensive and any means by which these costs or facilities can be simplified greatly contribute to-the commercial interests of the process.

Summary of the invention Generally speaking, the present invention is concerned with a method of recovering a high V.I. lube oil product from a lube oil crude to the exclusion of undesired constituents by a solvent extraction process in an environment which emphasizes the solvent selectivity arid-improves the yields of a lower V.I.' lube oil product recovered simultaneously therewith. Thus the present invention is particularlyconcerned with the method and combination of processing steps for producing lubricating oil prod.-

ucts having at least different V.Ii levels; one of which has" the equivalent-of---a'-light neutral--VJ. -level upon dewaxing of at least about 120 V.I. or the equivalent of a heavy neutral V.I. level upon dewaxing of at least 115 and the other has a lower, V. I. level; but above V.I.

-In accordance wit on'e embodiment within the concept of, the present; invention, a,. lube oil crude fraction of hydrocarbon feed stock boiling above about 550,F. is contacted countercurrentlynwith solvent,such as furfural, in a first extractio'ri column comprising a plurality of separate and sequentially arranged extracting'steps under conditions of temperature,andnisolvent.concentration to improve the solvent selectivityand permit recovering therefrom a primary lube'o'il raflinatefractio'mwhich will produce upon dewaxing :alube;QiL productof at least 90 V.I. and-preferably at least about .-V.I.' The. primary raffinate fraction thus separated". from. thefirstextractor and prior towdewaxingviswpass'ed in;..par,t or all. thereof :to a second extractor comprising a plurality: of: sequentially arranged separate extraction stages:;In the 'second extractor the selectivitywconditions ofthe-fu-rfuralisolvent are maintained beyond: that hereinbefore-thought economic by employing solvent-to oil ratiosof at least .711. andprefer'ably as high as possible and of the order of about- 10:1 so as torecover from the primary raflinate phase a secondary raffinate lube oil product phase whichis stable to oxidation and light while providing upon dewaxing a lube oil product having the equivalentof a light neutral V.I. level of at least -and preferably as 'high as about'125'V.I. By the above combination in-which a relatively high V.I. primary rafiinate of at least 90-V'.I. is further subjected to a very selective'solvent extraction operation under such conditions of'highsol-ventto oil ratio, it has been found that the overall solvent'do'sagerequirements of the process can be "held' to-a'desiredminimum and substantially reduced volumewise over that required to produce the highest V.I. oil desired in, for example, a single extractor column. Thus itcan be 'seen that-the extraction sequence above described and concerned with the essence of the present invention departs'significantly from the known prior art by employing'solvent dosages in at least one step which i'sffar above that employedhereinbefore and is generally in excess of about 8:1 with respect to'the oil phase being treated-so as to maximize" the selectivity of the furfural solvent. A second phase of the present invention is cOncerned with the treatment given the second extract phase 1 of the processsothat'the process is integrated in an economically attractive manner for'commercial application. In this" regard the secondary extract fraction'is cooled, add an anti-solvent such as "water or both to a temperature whichis-suitableifor releasing fromthe solvent an oil rich phase of desired V.I upon dewaxing. The oil phase may be-separatedby decanting soas to recover from this secondaryextra'ct the desired first'oil 'rich phase or fraction which issuitablefor use*or' blendingwith'at least a portion of the first rafiinate 'phase from a concentrated solvent "fractionorsolvent rich phase. It has been found that this decantedfirst oil'rich phase is of a composition which is 'suitable' fOnu's'e as is or it frnay be used for blending with the primary raffinate product obtained from the first extractor andused'toproduce the lube oil of lower V.I.

above about 90, thus contributing toan overall yield improvernent inthe'oil products attained from the hydrocarbon charge. The decanted solvent rich phase obtained fromthejsecond' extract is recovered and *all or a portion thereof is passed directly; after adjusting its temperature,

for use in thefirstextractor of the process either alone or'in combination with somefre'sh' makeup furfural. It is contemplated however taking a portion of'this decanted 'solvent' rich phas'e'an'cl'purifying'itby passing it to a solyentrcovery system wherein anaromatic rich oil phase is recovered fr'om the solventphase' and Ya purified solvent is recovered'w. hji'naybe' recycle'd'all' or in part to either the first or second extractor as desired. On the other hand, if all of the decanted solvent rich phase is passed to the first extractor, the first extract phase will then be treated in a suitable solvent recovery system to recover a purified solvent rich phase from an aromatic rich oil phase. In the arrangement of the process above described, it is to be particularly noted that a significant portion of the process above described is particularly concerned with and directed to improving the overall economics of the process by minimizing the volume of solvent required, the solvent recovery stages required and taking advantage of the improved selectivity of the solvent rich second extract phase to obtain not only the solvent requirement of the first extractor but also to recover from the second extract those oil constituents which are suitable for blending with an oil product recovered from the first raffinate phase.

Thus it can be seen that significant economic advantages and solvent selectivity are realized by the method and combination of process steps of the present invention. In conjunction with maximizing the selectivity of the furfural solvent, the present invention permits the recovery of the unusually high V.I. contributing constituents of oil crude sources in a manner not heretofore realized as economically attractive.

Thus the particular method of operation and combination of processing steps is selected so as to realize solvent selectivity and economic advantages only possible by the particular process combination herein described and highly suitable for commercial, application.

Brief description of the drawing Description of specific embodiments Referring now to the drawing, by way of example, there is provided an arrangement of processing steps for producing lube oil fractions from a hydrocarbon charge material such as a lube oil containing distillate fraction obtained from a Kuwait charge oil. In the arrangement of the drawing, a 120 SSU at 130 F. distillate fraction of a Kuwait crude is introduced by conduit 2 to a first extractor 4. Extractor 4 is provided with at least 5 stages of contact with furfural introduced to an upper portion of extractor 4 by conduit 6. In the operation of extractor 4, furfural is introduced to the upper portion of the extractor for countercurrent flow therein with the distillate charge introduced to the lower portion of the extractor, under conditions to maintain a temperature therein selected from within the range of from about 125 'F. to

about 210 F. and preferably of the order of about 190 F. An extract phase is Withdrawn from the bottom of the tractor 4 by conduit 10. A portion of the first or primary raffinate phase in conduit 10 is passed by conduit 12 to a dewaxing section 14. The remainingportion of the primary rafiinateinconduit- 10 is passed to a second extrac-- tor 16 and comprising 7 extraction stages. In extractor 16 the solvent extraction conditions are maintained sufiiciently intense or severe by using a large excess of furfural to remove from the primary rafiinate product a sufiicient amount of the low V.I. producing constituents of the primary rafiinate comprising paraffins in conjunction with high boiling polycyclic aromatic compounds not desired in the high V.I. lube oil product being produced. In extractor 16 it .is contemplated employing a large excess and from about 800 to about 1500% furfural to effect the intensity of extraction desired at a temperature maintained as low as possible and within the range of 175 to about 250 F; A temperature above about 225 F. is regarded as an excessive temperature for treatcomposition suitable for combining with the oil in the ment of light neutrals. In the specific arrangement of the drawing, sufficient furfural solvent is introduced into the upper portion of extractor 16 by conduit 18 for counter current flow therein to the primary raflinate introduced to the extractor by conduit 10.'The rafiinate phase of extractor 16 and comprising the secondary rafiinate is removed from the upper portion of extractor 16 by conduit 20. This secondary rafiinate is passed after stripping of solvent therefrom to a dewaxing zone 22 maintained at a sufficiently low dewaxing temperature such as about 20 F. in a specific embodiment. Wax is recovered from the dewaxing zone 22 by conduit 24 and a dewaxed oil of about 123 V1. is recovered by conduit 26'. The secondary extract phase obtained by extractor 16 is removed from the bottom thereof by conduit 28 for passage to a cooling zone 30 and conduit 32 to a separation zone 34. Separation zone 34 is maintained at a temperature of about P; so as to recover a parafiin rich oil phase separated from an aromatic rich extract phase. The parafiin rich oil or rafiinate phase thus separated is removed from separator 34 by conduit 36 and is passed to dewaxing zone 14 either alone or in combination with the portion of the primary raflinate in conduit 12 being passed to the dewaxing zone. In a specific embodiment, dewaxing zone 14 is maintained at a temperature of about 0 F. so as to recover wax from the oil product. In this specific embodiment, an oil product of about 95 V1. is recovered from dewaxing zone 14 by conduit 38 and the wax product is removed therefrom by conduit 40. The aromatic rich extract phase developed in separation zone 34 is removed from the lower portion thereof by conduit 42. The armoatic rich extract in conduit 42 may be combined with the extract phase in conduit 8 or may be separately processed to recover solvent from aromatic product. In the specific arrangement shown, the mixed extract phase is passed by conduit 44 to a furfural or'solvent stripper 46. Solvent is recovered from the upper portion of stripper 46 by conduit 48 and an aromatic rich oil phase is recovered from the bottom of stripper 46 by conduit 50. In the arrangement of the drawing, above described, it is to be understood that all or a part of the primary rafiinate phase in conduit 10 may. be. passed to the second extractor 16 and the amount passed thereto may be contingent, at least in part, upon the volumes of high and intermediate lube oil products desired by the individual refiner. It is also to be understood that a furfural stripper is necessary in conduits 20 and 12 prior to passing the oil product to thedewaxing step and such furfural strippers being known in the prior art are part of.this invention only to the extent required to recover solvent from the desired oil product. The

specific processing scheme, above described, departs from the known prior art in the concept of operating the secondary extractor under such intense conditions of extraction severity so as to permit recovery of a secondary 'rafiinate phase which upon dewaxing will provide a desired 0 F. pour, high V.I. lube oil product of at least about V.I.-Thismethod ofoperating-thesecond extractorunder such intense conditions of severity and high concentrations of fu rfural in combination with the recovery of oil products from the secondary extract of a primary raffinate portion and used to prepare the intermediate lube oil of about 95 V.I. and 20 F. pour is a significant departure from the known prior art.

Example I I Raw and dewaxed High Pour Libyan (HPL) 114 SSU v at F. distillates were furfural extracted at high fur- 3,488,283 7 8 dewaxing of 125 V1. Eifecting a similar solvent treatment extractor process hereinbefore described. It will be notedat 500% dosage produced a 113 V1. oil product, The from Table 2 that the raflinate from extractor No. 1 is yield obtained varied from 2.62.9% volume on crude used as charge to the extractor No. 2. It is also to be for the 125 V.I. oil to 4.1-4.6% for the 113 V.I. oil. noted that by effecting the solvent extraction in the two Examplen I v extractor system as hereinbefore described that considerable economic savings can be realized in the amount of Table 1 below presents the results of solvent furfural solvent required since the barrels of rafiinate charged to extraction at high furfural dosages of at least :1 .when the second extractor wherein the high solvent dosage is efiected in the manner described with respect to Exemployed is considerably less than when carrying out the ample I for other charge stocks identified in the table. 10 same solvent dosage in a single extractor system-such as It is to be noted that the high solvent dosages produced presented by Table 1. l V.I. oils of at least 120 irrespective of the crude employed. a

Example IV TABLE 1.- 125 v1" LIGHT NEUTRAL LUBES FROM a t 1 VARIOUS CRUDES BY DEEP FURFUBAL EXTRACTION. .Table 3 below presents the results obtalned when preparing a 1118 V.I. heavy neutral from a 453 SSU at 130 Crude Source F. Kuwalt dlstlllate by deep solvent extractlon withfur- High Beaummt fural. The data of the table is arranged similarly to that Libyan Kuwait MOS I I P d v presented m Table 2 for purposes of compar1son. Thus S00 0118: ifif g dosage, percent v01 1,000 1' 000 1 000 n th1s example it lS hOWI1 thatthe two. extractor system Temperature, F- 200 I 175 220 1s capable of producmg two different V.I. lube 011 prodgfig p Stages- 7 5 5 ucts of 94 and 118 V1. and the dewaxed oil separated ge v1s., SUS/130 92.6 114 115 Yields, percent voL: i from the second extract has a V.I. of 93 and this 1s suit- 8: g flfiff f fi if f? 2 5% $2 able for blending with the 94 V.I. product obtained from Finished an, on crude 2.9 2.1 t 1.6 the first extractor and it may be used in place thereof. P ggggggegeg 350 3M 35A Thus the method and combination of processing steps Pour point, "F 20 25 2c of th1s 1nvent1on permit the preparation of two different 156 139 199 V1. lube oil products by passing all or a portion of the 45.0 v 43.1 48.2 first raflinate to the second extractor so that a high V.I. 1g? 13?, 1 1% lube oil product can be, recovered from the second raf- 01: OK OK finate and a lower V.I. lube oil product can be separated Sample in c1ear4oz. bottle on window slllior 3months. a t' :lther or both of the first rafiinate and the Second v ex rac Example III 7 Y Having thus provided a general description of the method and processof the present invention and provided Table 2 below presents the results obtained when pre specific examples in respect thereof, it is to be noted that paring a 123 V1. light neutral by deep solvent exno undue restrictions are to be imposed by reason thereof tracting 114 SSU at 130 F. Kuwait distillate in the two except as defined by the appended claims.

TABLE 2.-123 VI LIGHT NEUTRAL FROM A 114 SSU AT 130 F. KUWAIT DISTILLATE BY DEEP FURFURAL EXTRACTION Extractor No. 1 a Extractor N0. 2 Extract No. 2 Separation (A) (B) Charge Raw Waxy Dewaxed Waxy (B) Dewaxed Waxy Dewaxed Dist. Ralf. Extract Oil Rafi. Extract Oil Rafi. Extract Oil Process conditions:

Furtural, percent vol Temperature, F- Extraction stages. 'Dewaxing tem1p., F

Yields, percent 170 On turiural extraction 61. 0 39. 0 0n dewaxing Finished oil, on dist 100 Properties: 7 e e we Gravity, API 23. 0 30. 8 12. 2 29. 1 Pour point 25 Viscosity:

SSU/ F 763 SSU/130 F 114 89. 8 SSU/210 F, 59. 1

Viscosity index .1

Flash point, F 460 TABLE a.11s v1 HEAVY NEUTRAL FROM A 453 set; AT 130 F. KUWAIT DISTILLATE BY DEEP FUR'FURAL EXTRACTION Extractor No. 1 v Extractor N o. 2 Extract No. 2 Separation I 8 Charge Raw Waxy Dewaxed Waxy (B) Dewaxed Waxy Dewaxed p Dist. Rafi. Extract Oil Raff. Extract Oil Rafi. Extract Oll Process conditions:

Furiural, percent vol.. Temperature, F... Extraction stages- Dewaxing temp, F..

Yields, percent On furiural extraction 100 On dewaxing Finished oil, on dist 100 Proper'tiesz Gravity, API 19. 5 Pour point, F- 115 Viscosity:

SSU/100 F. SSU/ 453 SSU/210 F--. 84. 6 Viscosity index Flash point, F

We claim:

1. A method for producing lubricating oils by solvent extraction which comprises:

(a) contacting a lube oil containing hydrocarbon charge material with solvent in a first extraction zone containing a plurality of separate extraction stages runder conditions of solvent selectivity to permit recovering :a first lube oil raflinate phase which upon dewaxing will provide a lube oil product of at least about 90 V.I.,

(b) further contacting a portion of the first lube oil raflinate phase in a second extraction zone containing a plurality of separate extraction stages under conditions of solvent selectivity attainable only by employing solvent to oil ratios of at least about 7 to 1.

(c) recovering a second lube oil raffinate phase from said second extraction zone which upon dewaxing will provide a lube oil product having the equivalent of a light or heavy neutral oil V.I. rating of at least about 115,

(d) recovering an extract from said second extractor,

(e) cooling and decanting said extract under conditions of temperature which permit the recovery of an oil phase having upon dewaxing a V.I. of at least about 90 and suitable for blending with a dewaxed lube oil product obtained from the first rafiinate phase and (f) passing a portion of a solvent rich phase remaining from decanting said extract to said first extractor as a substantial portion of the solvent requirements thereof.

2. The method of claim 1 wherein from about 130 to about 200 volume percent of solvent is employed in the first extractor and from about 700 to about 1500 volume percent of solvent is employed in the second extractor.

3. The method of claim 1 wherein the solvent is furfural and the temperature of the extractors is maintained in the range of from about 175 to about 250 F. and the temperature is maintained below about 225 F. when processing light neutrals.

4. The method of claim 1 wherein the solvent to oil ratio is at least 10 to 1.

5. The method of claim 1 wherein the dewaxed second raffinate provides a lube oil product having the equivalent of a light neutral oil V.I. rating of about 125.

6. The method of claim 1 wherein the dewaxed second raflinate provides a lube oil product having the equivalent of a heavy neutral oil V.I. rating of at least about 115.

7. The method of claim 1 wherein the solvent is selected from the group consisting of phenol, S0 and furtural.

8. The method of claim 1 wherein all of the first rafiinate is passed to the second extractor.

9. The method of claim 1 wherein a portion of the first rafiinate is dewaxed to produce a lube oil product of at least about VI. and the remaining portion of the first raffinate is passed to the second extractor.

10. The method of claim 1 wherein a second extract is recovered from the first extractor and stripped to recover solvent from an aromatic rich oil phase and said stripping is effected with or without a portion of the solvent rich phase recovered from said decanting step combined therewith.

11. The method of claim 1 wherein all of the lube oil product containing streams are stripped of solvent before effecting dewaxing thereof.

References Cited UNITED STATES PATENTS 2,054,433 9/1936 Manley 20836 2,161,567 6/1939 Gee et al 2083 16 2,165,638 7/1939 Manley 20836 2,952,610 9/1960 Fear 20836 2,953,501 9/1960 Mignone 208317 3,205,167 9/1965 Demeester 208327 HERBERT LEVINE, Primary Examiner US. Cl. X.R. 20818, 36, 327

mg? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 68283 Dated January 6, 1970 Inventor(s) HAROLD O. BUTTON and THEODOR A. PETRY It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Columns 7 and 8, Table 3. Under"Extractor No. 2",

(A) Waxy Raff. (line 13 of Table) 33.6" should be --34.6--

SIGNED AND SEALED MAY 121973 N... Attest:

Edward M. Fletcher, It. IWKLLIWM E." 'SCKHUYLER, m-

Anesting Officer Comissiozm of Pa imifi 

